In postmenopausal women with early-stage estrogen receptor-α (ERα)-positive breast cancer (ER+), the selective estrogen-receptor modulator (SERM), tamoxifen (TAM) represents a major adjuvant treatment in clinical practice. Many of the breast tumors that initially respond to the TAM therapy eventually develop resistance and recur. Among the patients with breast cancer with acquired resistance, only 20% of patients who progress on TAM respond to the selective ER down-regulator, fulvestrant, or to aromatase inhibitors even if ERα expression is maintained and regulates tumor proliferation.
Homeobox genes are regulatory genes encoding nuclear proteins that act as transcription factors during normal development and differentiation. One of these, HOXB7, is involved in a variety of developmental processes, including hematopoietic differentiation and lymphoid and mammary gland development. The role of HOX genes in breast cancer development is largely unexplored.
A need, therefore, still exists a need for improved treatment of TAM resistant breast cancer.